From 76a42e09f23cd6eec69e91d37e8c4a4f20b3488e Mon Sep 17 00:00:00 2001
From: Saurabh Kumar Bajpai <157192462+saurabhhhcodes@users.noreply.github.com>
Date: Thu, 28 May 2026 06:05:53 +0530
Subject: [PATCH] fix: add centralized backend error handling

---
 backend/middleware/errorHandler.js | 30 ++++++++++++++++++++++++++++++
 backend/routes/message.routes.js   | 23 ++++++++++++++++-------
 backend/routes/user.routes.js      | 27 ++++++++++++++++-----------
 backend/server.js                  |  6 +++++-
 4 files changed, 67 insertions(+), 19 deletions(-)
 create mode 100644 backend/middleware/errorHandler.js

diff --git a/backend/middleware/errorHandler.js b/backend/middleware/errorHandler.js
new file mode 100644
index 0000000..880d2fa
--- /dev/null
+++ b/backend/middleware/errorHandler.js
@@ -0,0 +1,30 @@
+export const asyncHandler = (handler) => (req, res, next) => {
+  Promise.resolve(handler(req, res, next)).catch(next)
+}
+
+export const notFoundHandler = (req, res, next) => {
+  if (res.headersSent) return next()
+
+  res.status(404).json({
+    message: `Route not found: ${req.method} ${req.originalUrl}`,
+  })
+}
+
+export const globalErrorHandler = (err, req, res, next) => {
+  if (res.headersSent) return next(err)
+
+  const statusCode = err.statusCode || err.status || 500
+  const isServerError = statusCode >= 500
+
+  if (isServerError) {
+    console.error("Unhandled API error:", err)
+  }
+
+  res.status(statusCode).json({
+    message: isServerError ? "Internal server error." : err.message,
+    ...(process.env.NODE_ENV === "development" && {
+      error: err.message,
+      stack: err.stack,
+    }),
+  })
+}
diff --git a/backend/routes/message.routes.js b/backend/routes/message.routes.js
index 5103314..97d1cb8 100644
--- a/backend/routes/message.routes.js
+++ b/backend/routes/message.routes.js
@@ -1,5 +1,6 @@
 import express from "express"
 import { protectRoute } from "../middleware/auth.js"
+import { asyncHandler } from "../middleware/errorHandler.js"
 import {
   getMessages,
   getMediaMessages,
@@ -35,7 +36,7 @@ const messageRouter = express.Router()
  *       500:
  *         description: Internal server error
  */
-messageRouter.get("/", protectRoute, getUserForSidebar)
+messageRouter.get("/", protectRoute, asyncHandler(getUserForSidebar))
 
 /**
  * @swagger
@@ -60,7 +61,7 @@ messageRouter.get("/", protectRoute, getUserForSidebar)
  *       500:
  *         description: Internal server error
  */
-messageRouter.get("/media/:userId", protectRoute, getMediaMessages)
+messageRouter.get("/media/:userId", protectRoute, asyncHandler(getMediaMessages))
 
 /**
  * @swagger
@@ -85,7 +86,7 @@ messageRouter.get("/media/:userId", protectRoute, getMediaMessages)
  *       500:
  *         description: Internal server error
  */
-messageRouter.get("/:userId", protectRoute, getMessages)
+messageRouter.get("/:userId", protectRoute, asyncHandler(getMessages))
 
 /**
  * @swagger
@@ -112,7 +113,11 @@ messageRouter.get("/:userId", protectRoute, getMessages)
  *       500:
  *         description: Internal server error
  */
-messageRouter.put("/mark-as-seen/:messageId", protectRoute, markMessagesAsSeen)
+messageRouter.put(
+  "/mark-as-seen/:messageId",
+  protectRoute,
+  asyncHandler(markMessagesAsSeen),
+)
 
 /**
  * @swagger
@@ -150,8 +155,12 @@ messageRouter.put("/mark-as-seen/:messageId", protectRoute, markMessagesAsSeen)
  *       500:
  *         description: Internal server error
  */
-messageRouter.post("/send/:receiverId", protectRoute, sendMessage)
-messageRouter.put("/edit/:messageId", protectRoute, editMessage)
-messageRouter.delete("/delete/:messageId", protectRoute, deleteMessage)
+messageRouter.post("/send/:receiverId", protectRoute, asyncHandler(sendMessage))
+messageRouter.put("/edit/:messageId", protectRoute, asyncHandler(editMessage))
+messageRouter.delete(
+  "/delete/:messageId",
+  protectRoute,
+  asyncHandler(deleteMessage),
+)
 
 export default messageRouter
diff --git a/backend/routes/user.routes.js b/backend/routes/user.routes.js
index c811479..46694f9 100644
--- a/backend/routes/user.routes.js
+++ b/backend/routes/user.routes.js
@@ -13,6 +13,7 @@ import {
   loginGuest,
 } from "../controllers/user.controller.js"
 import { protectRoute } from "../middleware/auth.js"
+import { asyncHandler } from "../middleware/errorHandler.js"
 import { validateBody } from "../middleware/validate.middleware.js"
 import {
   signupSchema,
@@ -79,7 +80,7 @@ const userRouter = express.Router()
  *       500:
  *         description: Internal server error
  */
-userRouter.post("/signup", validateBody(signupSchema), signup)
+userRouter.post("/signup", validateBody(signupSchema), asyncHandler(signup))
 
 /**
  * @swagger
@@ -117,7 +118,7 @@ userRouter.post("/signup", validateBody(signupSchema), signup)
  *       500:
  *         description: Internal server error
  */
-userRouter.post("/login", validateBody(loginSchema), login)
+userRouter.post("/login", validateBody(loginSchema), asyncHandler(login))
 
 /**
  * @swagger
@@ -135,10 +136,14 @@ userRouter.post("/login", validateBody(loginSchema), login)
  *       500:
  *         description: Internal server error
  */
-userRouter.post("/refresh", refresh)
-userRouter.post("/logout", logout)
-userRouter.post("/send-otp", validateBody(sendOTPSchema), sendOTP)
-userRouter.post("/verify-otp", validateBody(verifyOTPSchema), verifyOTP)
+userRouter.post("/refresh", asyncHandler(refresh))
+userRouter.post("/logout", asyncHandler(logout))
+userRouter.post("/send-otp", validateBody(sendOTPSchema), asyncHandler(sendOTP))
+userRouter.post(
+  "/verify-otp",
+  validateBody(verifyOTPSchema),
+  asyncHandler(verifyOTP),
+)
 /**
  * @swagger
  * /api/v1/auth/guest-login:
@@ -169,18 +174,18 @@ userRouter.post("/verify-otp", validateBody(verifyOTPSchema), verifyOTP)
  *       500:
  *         description: Internal server error
  */
-userRouter.post("/guest-login", loginGuest)
+userRouter.post("/guest-login", asyncHandler(loginGuest))
 userRouter.post(
   "/forgot-password",
   validateBody(forgotPasswordSchema),
-  forgotPassword,
+  asyncHandler(forgotPassword),
 )
 userRouter.post(
   "/reset-password",
   validateBody(resetPasswordSchema),
-  resetPassword,
+  asyncHandler(resetPassword),
 )
-userRouter.get("/check-auth", protectRoute, checkAuth)
+userRouter.get("/check-auth", protectRoute, asyncHandler(checkAuth))
 
 /**
  * @swagger
@@ -218,7 +223,7 @@ userRouter.put(
   "/update-profile",
   protectRoute,
   validateBody(updateProfileSchema),
-  updateProfile,
+  asyncHandler(updateProfile),
 )
 
 export default userRouter
diff --git a/backend/server.js b/backend/server.js
index ca2fc08..2522f07 100644
--- a/backend/server.js
+++ b/backend/server.js
@@ -16,6 +16,7 @@ import ChallengeRoom from "./models/ChallengeRoom.js"
 import { Server } from "socket.io"
 import { isVercel, parsePort, getPlatform } from "./lib/runtime.js"
 import { registerTypingHandlers } from "./typingHandler.js"
+import { globalErrorHandler, notFoundHandler } from "./middleware/errorHandler.js"
 
 const app = express()
 const server = http.createServer(app)
@@ -319,10 +320,13 @@ app.use("/api/v1/messages", standardLimiter, messageRouter)
 app.use("/api/v1/problems", standardLimiter, problemRouter)
 app.use("/api/v1/challenges", standardLimiter, challengeRouter)
 
-app.use("/", (req, res) => {
+app.get("/", (req, res) => {
   res.send("NPMChat API is running")
 })
 
+app.use(notFoundHandler)
+app.use(globalErrorHandler)
+
 // 5. Database Connection
 if (process.env.NODE_ENV !== "test") {
   connectDB()